Spectral evolution of galaxies. I. Early-type systems.

This work develops models for the spectral evolution of early-type galaxies using population synthesis techniques. Different choices of the initial mass function and the star formation rate allow the construction of models which at the present epoch cover the range of observed galaxy spectra. Special emphasis is given to the ultraviolet region of the spectrum. Ultraviolet spectra of late-type stars and early-type galaxies obtained with the International Ultraviolet Explorer satellite are used in this work. The evolving spectral energy distributions are used to compute galaxy colors, magnitudes, K-corrections, and evolutionary corrections as functions of redshift for different photometric systems.